End Plug Welding of New FM Cladding Tube for SFR Metallic Fuel Rod

Ferritic/martensitic (FM) steel such as HT9 has been selected for a SFR fuel cladding tube material because of the excellent irradiation characteristics. But the HT9 material is not enough to satisfy the discharge burnup goal due to the high coolant outlet temperature and the low creep resistance. Recently new FM steel is under development to improve HT9 material properties. At KAERI, development of new FM steels, named FC92B and FC92N, has been in progress to improve thermal creep resistance. In this study, the qualification test of the end plug welding of new FM steels, FC92B and FC92N, for SFR metallic fuel rods was carried out based on the developed HT9 welding technology. Through the qualification test, the end plug welding of new FM steels was well verified. Through the qualification test, the weld quality of end plug welding of new FM cladding tubes, FC92B and FC92N, was evaluated according to the qualification test plan and satisfied the requirements on the weld. Consequently, the qualified welding process is ready to produce SFR metallic fuel rods